To Fight Malaria, Skip the Beer?

If you’re trying to avoid mosquito bites, try skipping the beer. Scientists randomly assigned 43 men in Burkina Faso to drink either a locally brewed beer or tap water. They found that the mosquitoes were more attracted to the beer drinkers than the water drinkers. The study’s authors conclude that “beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.” (HT: Chris Blattman) [%comments]


Jenny

Ah ha --- interesting -- could it be the link between drinking beer outside at night when anopheles bite or really that they are attracted to beer?

nop

Anyway if Iyou're trying to avoid cholera, try skipping tap water in Africa ;)

Jake

Beer contains carbon dioxide. Mosquitos are attracted to carbon dioxide emitted by warm blooded animals. The beer drinkers are probably emitting more carbon dioxide than the non-beer drinkers which would make them more attractive to the mosquitos.

Eliminating beer drinking will not stop the mosquitos from biting. Rather, We might just see a more even distribution of bites amongst the people.

Greg Finley

Anyone else concerned about the small sample size?

levi

Did they all drink the same local beer? If so, it could be something with that beer.

chrislrob

I'll be needing more proof than that to stop drinking beer.

Hamed

I see this as conclusive proof that I should switch to drinking spirits when on my holidays. My heartfelt thanks to the 43 men in Burkina Faso who made this happen.

Grant

Good thing I don't plan on going to Burkina Faso.

vincent

I think the conclusion is superfacial. What if those who used to drink beer stop drinking beer and those who used to drink water start drinking beer?

Devin

The interesting question is the one Jake posed (above). Similarly, would drinking a nitrogenated beer (Guinness) solve this problem?

Dorophy

I never ever drink beer, but why the mosiquitoes love me so much? hehe

Zack

If you actually read the summery of the article it says that beer drinking increases body odor which attracts the mosquitoes and not CO2 emission.

#2 that was pretty funny

Kas

Avoid fruit juice as well or anything that has high sugar content.

Chris

Interesting. Just yesterday I read a column that said if you want to scare away mosquitoes you should take brewer's yeast. Seems a bit contradictory.

kip

My guess at the cause, though I'm not a doctor or entomologist, is that alcohol causes widening of blood vessels, which causes the body to give off more heat, which attracts mosquitoes.

Jerry Tsai

@Greg Finley,

Without reading the analysis, actually the sample size is not horrible, though yes more would certainly be better, although they certainly could have improved the design of the study by having the same men drink water one night and beer another night. That way one could much better account for individual attractiveness to mosquito bites, rather than hoping that randomization will reveal a true causal effect.

So either do the study they did with 100 men (50 in each group) or use 50 men, with 25 drinking beer and 25 drinking water and then have the same 50 men switch beverages on another night.

Ron

I believe it. As a kid I never got mosquito bites. But since reaching legal drinking age I get torn up by skeeters. Ironically, usually when I am outdoors in mosquito pron areas, I am drinking beer.

Gavin Brown

I was told by people that worked in Nigeria that one of the worst things you could do was get so drunk that you got a hangover the next day, because Malaria symptoms are similar to a bad hangover.

Therefore if you have a big night out and contract Malaria, you may end up confusing the two and by the time you realise there is something wrong, it may be too late...

James

Maybe gin and tonics instead? Quinine = no malaria.

Roger

I rarely bother to read these sorts of studies any more, because they are nearly all bunk. But when I do read them, I like to read ALL their results, because it tends to give a bit of a clue as to how reliable the study may be (usually, not very reliable at all.)

This study DOES seem to show that beery odours, at least for a certain type of beer, are more likely to both "activate" and "orientate" mosquitoes -- at least, for a certain type of mosquito that is important in West Africa. However the effects are weak (in one case the 95% confidence interval overlaps that for the "no treatment" scenario, in the other case it just barely misses out overlapping), but does seem to be statistically significant, at least at the pathetic 5% level, assuming nothing is amiss behind the scenes.

But it shows a few other things too, and some of them seem surprising, perhaps even unlikely. It shows that when you set up a Y-olfactometer to pump human odours toward famished female mosquitoes, only about a third are interested at all. Strange.

Even stranger, of the one third who seem to be interested, it appears that they cannot tell which way the tasty meal is UNLESS the victim has been drinking beer. I guess it's lucky that Fred Flintstone introduced humans to beer millions of years ago, or mosquitoes could never have evolved!

Stranger and stranger: drinking water weakly repels mosquitoes, as does CO2 in exhaled human breath (unless it has beer fumes in it.) More specifically, the CO2 content in exhaled breath has no effect in luring the mozzies into the olfactometer, but once they are in, they slightly tend to avoid it. Huh?

There is a difference in the mosquito attractiveness of particular individuals (speaking as a mosquito magnet myself, I have to say a big "Well, duh!" to that) and this effect is MUCH LARGER than the effect of drinking beer. More peculiarly, there is no correlation between subjects who strongly activate mosquitoes, and those who strongly orient them. That is, there are people who drive the mozzies mad with hunger, but then cannot be found; and there are people whom the mozzies do not care for, but they track relentlessly. Huh?!

The authors do not bother to discuss at all the fact that these interpersonal variations are much stronger than the beer effect. Apparently the beer effect is more interesting because alcohol consumption is evil (even the very weak beer in this study ...)

In the discussion section, some of these anomalies are mentioned. The strangely negative effects of CO2 are possibly attributable to the high concentration, which may be repellent to mozzies even though lower concentrations are attractive. (This makes a certain amount of sense: the mozzie can't just follow the CO2 stream indefinitely, or it will fly down your throat!) BUT: if that's the case, it could just as easily be the case with the beer fumes ....

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